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Packaging Large Scale JS projects with gulp

Large scale JS projects have become a lot more common with the rise of AngularJS and other javascript frameworks.

Laying out your project though you want to have your source in a lot of separate files to keep things neat and in a structure, but you don’t want you browser making a few hundred connections to the web server on every page load.

I previous blogged about a simple JS and CSS minify and compress for a C# based project, but this time I’m looking at a small AngularJS project that has over 50 js files.

I’m using VS 2015 with the Web Essentials add-on, so in the package.json file can put my npm requirements and they will download, with 2013 i previously had to run npm on my local each time I setup to get them, the new VS is way better for these tasks, if you haven’t upgraded to 2015 you should download it now.

There is 3 important files highlighted below

Firstly lets look at my package json file:

in here you can add all your npm dependencies and VS with run npm in the background to install them, as you are typing.

Next is the bower.json file

This is used for managing your 3rd party libraries, traditionally when throwing in 3rd party js libraries I would use a CDN, however with Angular, you will end up with a bunch of smaller libraries that will end you up with too many CDN references, so you are better off using bower to download them into your project, then from there combine them (They will already be uglifyd in most cases).

Now there is also a “.bowerrc” file that i have added, because i don’t like the default path

{
"directory": "app/lib"
}

Again as with the package json it will start downloading these as you type and press save, also to note it doesn’t clean up if you delete one, so you’ll need to go into the target location and delete the folder manually.

Lastly the Gulpfile.js file, here is where we bring it all together.

In the example below I am processing 2 lots of javascript, the 3rd party libraries into a lib.min.js and our code into scripts.min.js. I could also add a final step to combine them as well.

The good thing about the below is that as i add new js files to my /app/scripts folder, they automatically get combined into the main script file, and when a add new 3rd party libraries the will automatically get added to the 3rd party script file (hence the aforementioned change to the bowerrc file).

The 3rd party libraries tend to sometimes get painful though, you can see below that i am not minifing them only joining, the ones i’m using are all minified already, but sometimes you will get ones that aren’t, also one of the packages i am using contains the jQuery1.8 libraries that it appears to use for some sort of unit test, so i had to exclude this file specifically, so be prepared for some troubleshooting with this.

oh and don’t for get to add tehse fiels to your gitignore or tfignore so they don’t get checked in. and also make sure you add “note_modules” and your 3rd party library folder as well, you don’t want to be checking in your dependencies, I’ll do another blog post about using the above dependencies in the build environment.

Just to note, not having node_modules in my gitignore killed VS2015s integration with github causing a error about the path being longer than 260 characters. Prevented me checking in and refused to acknowledge the project was under source control.

You will also note in the above processing I have a source map file output, this is essential for debugging the scripts. These map files wont get download unless the browser is in debugging mode and you should use your build/deployment environment to exclude from production, to stop people decompressing you js code.

You can see from the screen shot below with me debugging on my local, firebug is able to render the original javascript code for me to debug and step through the code just like it was uncompressed, with the original file names and all.